History of Interstate 70 in Colorado

I-70 through the Glenwood Canyon.

Western Colorado

The highway is quite fragmented west of Denver, due to the mountainous terrain. In 1961, the first section opened around Idaho Springs, just west of Denver. In 1963, the first sections also opened at Grand Junction, all the way in western Colorado. Subsequently, the middle section at Vail was opened in the late 1960s. Then followed the intermediate parts, which were laid through very mountainous areas. This happened mainly in the 1970s through the main chain of the Rocky Mountains. On March 8, 1973, the first tube of the Eisenhower Tunnel was opened, after which the section through the Rocky Mountains was completed within 2 years.

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The part in western Colorado was more difficult. Although the mountains are less high here, the landscape is dotted with gorges and steep rock faces. The section between Grand Junction and Eagle in particular was difficult to construct. Although some parts were completed earlier, the construction of this part mainly took place in the 1980s, which relieved US 6 of its through function. On October 14, 1992, the last section was opened through the Glenwood Canyon. This is considered one of the most spectacular parts of the Interstate Highway system. This is also considered to be the completion of the last link of the Interstate Highway system.

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From Unpleasant Length Opening
Exit 239 Exit 242 5 km 1961
Exit 242 Exit 244 3 km 1961
exit 37 Exit 49 19 km 04-10-1963
Exit 30 exit 37 12 km 1965
exit 112 Exit 116 6 km 1966
Exit 232 Exit 239 12 km 1966
Exit 25 Exit 30 8 km 1967
Exit 171 Exit 176 8 km 1968
Exit 228 Exit 232 6 km 1968
Exit 176 Exit 190 23 km 1969
Exit 19 Exit 25 10 km 1969
Exit 167 Exit 171 6 km 1970
Exit 105 exit 112 12 km 1971
Exit 157 Exit 167 16 km 1971
Exit 11 Exit 19 13 km 1972
Exit 195 Exit 200 8 km 1972
Exit 216 Exit 228 19 km 1972
exit 0 Exit 11 18 km 27-09-1973
Exit 97 Exit 105 13 km 1973
Exit 147 Exit 157 16 km 1973
Exit 200 Exit 216 26 km 1973
Exit 87 Exit 97 16 km 1976
Exit 140 Exit 147 12 km 1979
Exit 190 Exit 195 8 km 1979
Exit 82 Exit 87 8 km 1980
exit 128 Exit 140 19 km 1980
Exit 76 Exit 82 10 km 1983
exit 62 Exit 76 21 km 1984
Exit 49 exit 62 21 km 1989
Exit 116 exit 128 19 km 1992

Eisenhower Tunnel

The Eisenhower Tunnel.

See also Eisenhower Tunnel.

A tunnel had to be built at the Continental Divide, the watershed between the Atlantic and Pacific Oceans, because the 3,800-meter high mountain range was too steep for a highway to cross. The construction of the first tunnel tube started in 1968. The tunnel opened with a delay in 1973 with one tunnel tube. The construction of the second tunnel tube lasted from 1975 to 1979. The tunnel is 2.7 kilometers long and is located at an altitude of 3,401 meters, at the time the highest road tunnel in the world. It is still the highest point of the Interstate Highway system. The entire tunnel cost 108 million dollars. The tunnel is an important connection between the metropolis of Denver and the ski areas around Aspen and Vail. The next freeway connection is 160 kilometers to the north ( I-80), or 710 miles south ( I-40 ).

Trucks over 4.10 meters in height cannot pass through the tunnel and must take the slow route via the 3,650 meters high Loveland Pass. Near the Eisenhower Tunnel is also the highest road in the United States, which leads to Mount Evans at 4,348 meters. The Eisenhower Tunnel replaced the old Loveland Pass over which US 6 passes.

Denver Metropolitan Area

The first section built by the Denver metropolitan area dates from 1964, a short distance north of downtown. The route through the east of the city was completed in 1966, a fairly easy section to build because the terrain is flat. The portion west of Denver opened primarily in the late 1960s and early 1970s, with the highway joining Idaho Springs in 1975 on the very first section of I-70 westward. In 1977, the last link east of Denver opened to traffic.

From Unpleasant Length Opening
Exit 274 Exit 276 3 km 12-09-1964
Exit 272 Exit 274 3 km 10-12-1965
Exit 276 Exit 281 8 km 1965
Exit 281 Exit 288 11 km 1966
Exit 271 Exit 272 2 km 09-07-1966
Exit 269 Exit 271 3 km 1967
Exit 266 Exit 269 5 km 1968
Exit 259 Exit 261 3 km 1969
Exit 261 Exit 266 8 km 1970
Exit 254 Exit 259 8 km 1970
Exit 248 Exit 254 10 km 1972
Exit 244 Exit 248 6 km 1975
Exit 288 Exit 295 11 km 1977

In eastern Denver, I-70 originally tunneled under a runway and two taxiways from Stapleton International Airport. The airport was moved to a location further outside the city in 1995, when the tunnel was demolished. This tunnel was at the intersection with I-270 and Central Park Boulevard.

Interstate 70 originally ran over an overpass in Denver through the north of the city. There were wishes to deepen I-70 here to reduce disruption to the surrounding area, and to expand highway capacity from 2×3 lanes to 2×5 lanes, including express lanes. The total project included 17 kilometers of I-70 between I-25 and Tower Road, the sunken section is 2 kilometers long between Brighton Boulevard and Colorado Boulevard.

The widened portion is the busiest segment of I-70 in the state of Colorado. On January 19, 2017, the Federal Highway Administration approved the project. In August 2017, the project was awarded to Kiewit Meridiam Partners, which reached a financial close of $2.35 billion on December 21, 2017. On April 3, 2018, objections to the project were rejected. Work started in August 2018. The widening between I-270 and I-225 will be completed in 2020. The first half of the sunken location was taken into use on 24 May 2021. On June 6, 2022, the express lanes of the project were put into use as a test. It was the largest road project in Denver in over 15 years.

Eastern Colorado

I-70 at South Canyon.

I-70 at Cameo.

The section through eastern Colorado was opened between Denver and Limon between 1963 and 1968. Also in the east of the state, the part of Seibert and the border with Kansas was opened between 1967 and 1971. Missing was a stretch from Limon to Seibert, which was finally opened in 1974 and 1975. The US 24 has been completely canceled here.

From Unpleasant Length Opening
Exit 295 Exit 304 14 km 1963
Exit 304 Exit 316 19 km 1964
Exit 316 Exit 328 19 km 1967
Exit 429 Exit 437 13 km 1967
Exit 328 Exit 340 19 km 1968
Exit 340 Exit 359 31 km 1968
Exit 437 Exit 449 19 km 1969
Exit 405 Exit 429 23 km 1971
Exit 395 Exit 405 16 km 1974
Exit 359 Exit 395 58 km 1975

express lane

I-70 west of Denver has massive congestion on Friday afternoons and Sunday afternoons, westbound Friday afternoon, and eastbound Sunday. The section between Idaho Springs and Denver already has 2×3 lanes. A 12-mile left rush -hour lane has been constructed on I-70 heading east from US 40 in Empire to Idaho Springs. This is an express lane where tolls are levied, the first rush-hour lane in the world where tolls apply. The rush hour lane was constructed between June 2014 and December 2015. The rush-hour lane was put into use on December 12, 2015. The rush hour/toll lane is expected to be in use 72 days a year.

In the first winter season of use, the express lane improved travel time in all lanes. The dynamic toll system maximized capacity, up to 3,100 vehicles per hour on 3 lanes, while still allowing a speed of 90 km/h. In the first season, tolls were mostly between $4 – 6, peaking at $8.

A rush-hour lane to the west was also constructed on the same route, which was taken into use on 31 July 2021.


Rocky Mountains

During the winter period, I-70 has a strong peak in traffic around the weekend to the winter sports areas west of the Eisenhower Tunnel. As a temporary measure, a toll lane was constructed in 2015 towards Denver over a small part of the route. In 2021, a toll lane will be constructed on the hard shoulder to the west.

Large-scale interventions are expected in the long term. The most logical option would be a 2-lane interchange lane that guarantees free-flow as an express lane with dynamic toll rates. Such a switch lane will probably be located next to the existing I-70 with a few tunnels. The disadvantage is that it is only profitable on Friday afternoon and Sunday afternoon/evening. There are also no plans to build this interchangeable track through the Eisenhower Tunnel. As a result, such a switch lane will be mainly useful for traffic to Winter Park, and less for traffic to ski areas such as Breckenridge, Copper Mountain, Vail or Aspen.

Between Floyd Hill and Idaho Springs, I-70 will be widened to 2×3 lanes. Currently, this stretch already has an express lane or 3 lanes toward Denver, but not west yet. The environmental report was made available for inspection on 2 August 2021. In January 2022, a contractor was selected to carry out the project for $700 million. Preparatory work started in 2022, with large-scale work starting in 2023.


The left rush hour lane on I-70 between Empire and Idaho Springs is used as a toll lane on peak days. The toll rates are different for vehicles with a transponder and without a transponder ( license plate toll ). The rates also vary depending on how busy it is. When opened, it was one of the most expensive toll roads in the world, with fares ranging from $3 in light traffic, to $15 in heavy traffic with a transponder, and up to $25 for license plate tolls. The express lane is 21 kilometers long. At peak times, a levy of more than $1 per kilometer applies with a license plate toll. Originally the toll was only towards Denver, but since July 7, 2022 also towards the west.

Traffic intensities

7,300 vehicles enter Colorado from Utah daily. 17,000 to 35,000 vehicles per day pass through the Rocky Mountains, as I-70 is the only high-speed route for miles around. 30,400 vehicles pass through the Eisenhower Tunnel daily. In Denver, of course, the intensity increases. 138,000 vehicles drive through Wheat Ridge, but after I-76, that number drops to 86,700 vehicles. Further on, that rises to 154,000 vehicles at I-25. In the north of Denver, the busiest point is reached with 179,000 vehicles per day. After Aurora, that quickly drops to 20,000 vehicles. In eastern Colorado, intensities barely reach 10,000 more, and 8,300 vehicles cross the Kansas border every day.

Lane Configuration

From Unpleasant Lanes Comments
exit 0 Exit 233 2×2
Exit 233 Exit 274 2×3 Denver
Exit 274 Exit 275 2×4 Denver
Exit 275 Exit 279 2×3 Denver
Exit 279 Exit 282 2×4 Denver
Exit 282 Exit 284 2×3 Denver
Exit 284 Exit 438 2×2

History of Interstate 70 in Colorado

History of Interstate 70 in Colorado
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